(a) Field of the Invention
The present invention relates to a display device, and in particular, to an electron emission display device having a grid electrode structure thereof which efficiently controls the travel course of electrons emitted from the electron emission source.
(b) Description of the Related Art
Generally, electron emission display devices are display devices that can be classified into two types. A first type uses a hot (or thermoionic) cathode as an electron emission source, and a second type uses a cold cathode as an electron emission source.
Also, in the second type of electron emission display devices, there are a field emission array (FEA) type, a surface conduction emitter (SCE) type, a metal-insulator-metal (MIM) type, a metal-insulator-semiconductor (MIS) type, and a ballistic electron surface emitting (BSE) type.
Although the electron emission display devices are differentiated in their specific structure depending upon the types thereof, they all basically have an electron emission unit placed within a vacuum vessel, and a light emission unit facing the electron emission unit in the vacuum vessel.
In the conventional FEA electron emission display device, as the electrons emitted from the electron emitting units travel toward the phosphor regions, there is a problem that the electrons are dispersed by influence of a driving voltage applied to the gate electrode.
To overcome the problem of electron dispersion, it has recently been proposed to use a grid electrode or a focusing electrode to control the travel course of the electrons emitted from the electron emitting unit.
This grid electrode or focusing electrode is mounted between the first substrate having the electron emitting unit disposed thereon and the second substrate having the phosphor portion disposed thereon. Particularly, the grid electrode is disposed while maintaining a uniform gap with the first substrate, and has a plurality of openings, each of which corresponds to one of the pixel regions formed on the first substrate.
In addition, although most electrons are emitted from edges of the electron emitting source and at predetermined angles toward the second substrate, conventional structure of the grid electrode has not been developed considering this point. As such, many of the electrons are unable to pass through the openings of the grid electrode and instead experience misdirection away from their intended paths.
Also, many electrons either arc toward the first substrate while colliding on the interior wall of the grid electrode, or fail to reach the intended phosphor portion. As a result, picture quality is significantly reduced.